Driving America in the right direction

Written by erin


I’ve commented before about a dilemma produced by fuel-efficient cars: they emit less per mile, but also make it less expensive to drive… creating a countervailing incentive to drive more than you might have in a gas guzzler.

Therefore I was happy to discover that the University of Michigan has been tracking and amalgamating the greenhouse gas emissions effects of both the emissions profile of new cars for sale, and the average number of miles driven on a monthly basis. They call the resulting trendline the “Eco-Driving Index.” They’ve been tracking it since 2007, when the EPA revamped its new-car fuel economy calculation methods.

Here’s what the trend looks like:

All the data is normalized to 2007, so if we were driving exactly the same distance, and new cars emitted exactly the same per mile today as in 2007, the index would be “1.00.”

As you can see, both “miles driven” and “fuel used per distance driven” have dropped, albeit not consistently. Still, drivers who bought a new car in May 2011 would, on average, emit 16% fewer greenhouse gases than drivers who bought new cars in October 2007.

My two conclusions: First, this is great. I’m glad to see that we haven’t gobbled up all our efficiencies by increasing our driving. Second, it’s clear that the bulk of the improvement comes from more efficient cars, not driving less. That’s the lever we have to continually adjust downward at a policy level.

You can find more details on the calculation method here.

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  1. HTB

    It would be helpful to me to hear (again?) various suggestions for strategies to drive less beyond the obvious eg car pool, mass transit, less trips to grocery store, etc.

  2. bezer

    When do we stop blaming the automobile for everything wrong with our enviorment ? the car is only part of the problem and one that is getting smaller at a huge cost to consumers in pollution control devices. Here is a better idea…. try using a push mower to mow your postage stamp lawns. Why use a gas powered mower? They have no pollution control devices, stink like crazy and in 1 hour of operation emit as many harmful pollutants as a car does driving 10 hours on the freeway. Get with the plan and focus on the small things we all can do to make things better faster. Replacing a car to increase fuel mileage by 20%, and reduce emissions is a very costly exercise to save so little. Replace the $400 gas mower with a $100 push , or a $350 Electric / Battery and you’ll be doing the atmosphere a bigger favor and a whole lot faster !!!

  3. Ray

    Agree with your comment. Cars are just part of the problem, there is lot more that needs attention.

  4. HTB

    Bezer, Great suggestion. I used a push, non engine mower at our last home. It was made in Germany. Easy to use and did a good job as long as you don’t let the grass get too high. You have prompted me to look into another one instead of the second hand, fume belcher I’m currently using.

  5. bezer

    I currently have about 1/3 acre lawn and use a battery pwoered mulcher from Black and Decker. I had a Toro battery mower before this … all in all for about 12 years now, 2 mowers-virtually no repairs (ok – my kid hit a landscape boulder and broke the wheel)- no gas, no tune ups- no oil- plug in, charges over night and goes.
    Only in early spring when lawn needs to be mowed 2x weekly, does it bog down from wet thick grass. We live in Michigan fyi

  6. HTB

    Bezer, You have enlightened me again. I thought the electric mowers only came with long cords. Apparently there are chargable ones like B&D. I’m sure these are better for high grass, though the straight push ones are quieter.

  7. Anonymous

    update for those interested…. “bing” or google “battery Lawn Mowers”. There are several mfg’s — some are sold at Home Depot, some direct from a Black and Decker store. If you go B&D, ask them for the “remanufactured units”. I bought one for about $100 less than than list because of over spray in the mfg process. A great deal.

  8. crx_rogus

    While it’s true that cars are only part of the global pollution problem, there’s the need to keep making real progress in backing away from our 96% transport dependency on petroleum, with about a quarter being from the Middle East… In shorter trips PHEVs easily get 100+ mpg, and even if those miles are purely coal-powered, it’s still less carbon transferred from underground to the sky than the equivalent gas/petrol burner would transfer.
    That said, I figure each July 4th all the charcoal BBQs nationally emit more CO than all the cars on the roads nationally for at least that month if not year, and more than my 2000 Insight will emit in its entire lifetime.

  9. bezer

    yep CRX – u r right in many ways. Then despite all our efforts to curb emissions, we have one big volcano erupt and that erases and effort all of us have tried for 30 years. Not to give up on the emission controls, but the burden on the consumer is huge.
    While your Insight is fuel and emissions efficient….Honda can never claim to be a real socially conscious company.Think about the motorcycles / both 2 stroke and 4 stroke, the ATV’s and 4 wheelers and all the gas power lawn equipment they make. None of it with a single thought of controlling emissions. …ugg – would want to re-think where I spend my $$ next time.

  10. crx_rogus

    Honda did well environmentally in the ’70s and ’80s with the CVCC lean-burn engine and all the truly great small cars of those years, but they somewhat lost their way with the later larger, heavier vehicles (mine’s a major EV1-inspired anomaly in that trend). I gather my car’s 1.0L IMA design will finally find a future in the upcoming Fit/Jazz hybrid… If they can get back to fun little cars they might be ok.
    As for all the little utility vehicles, if they run better than the competition, which they probably do, then they emit less pollution than the competition at least… which isn’t saying much. And motorcycles are of course what got Honda started, where its strength with agile little vehicles partly stems from… It’s hard getting weight down these days, but if people can remember resourcefulness and how much fun small cars can be, mpg will easily rise as small vehicles sales rise. Modern engine technology in vehicles with ’80s weights would have both great economy and performance, with VOC emissions etc. a tiny percentage of what they were from ’80s engines.

  11. Gary

    I *love* my rechargeable mower. I’ve been using a B&D for 4 years. It is a little heavier and has a touch less power, but it is much quieter than gas, no fumes, and no direct emissions! The only problem I had was when I dropped the charger and broke it.

  12. Anonymous

    Modern engine technology is a wonderful thing and continues to get better with each new iteration or invention (I think of the Ecoboost / turbo charger Ford now has). We all like lots of power-i think probably no one, if being honest can deny that. I am scared to ride in small cars (B Segment- like the Fit , Yaris, Fiesta) The fleet with which you have to compete with larger cars and trucks is still too large and will be that way for a number of years. (last time I read a figure of about 15% of fleet is C -Segment (Civic- Focus-etc..)The growth in C Segment cars is huge right now and should continue to grow. Ride quality is better than ever before in most(bad news for 2012 Civic- if you believe Cons Reports), but I can’t serious about a C size car due to family needs and safety factors. Enough rambling…. have a good day- nice chatting with you all.

  13. spencer

    It’s interesting that you assumed that because an individual drives a more fuel effecient and thus, more affordable automobile, one is inclined to drive more. This notion had occurred to me quite some time ago, but never as anything more than hype for naysayers.
    I, personally, drove a truck for several years. When I made the decision to trade it in for a diesel compact, I knew that my new, stretched dollar would technically enable me to drive further. However, I’ve always known that this paradoxical tendency had the ability to undo all of my respective goals.
    If anything, my better gas mileage has made me drive even less. Now, I work from home, use Garmin Ecoroute instrumentation, hypermile and even ride my bike some of the time.
    It’s my expertise that if a person’s heart is in the right place and if they understand gas mileage, their respective goals will be reached.
    Being informed is king.

  14. Anonymous

    75% of electricity in michigan is coal powered.

  15. Anonymous

    Electricity is dirty